Overheating - Make sure that your computer has adequate ventilation and the cooling fans are still operational and are not being blocked. Most computers will slow down the CPU when it starts to overheat, reducing performance considerably. Overheating can also cause your computer to crash or freeze. For a laptop, a DJ laptop stand is a recommended to allow all round ventilation.

Incorrect permissions on your VirtualDJ folder (This will may also prevent VirtualDJ saving the database, so your cue points, BPM, comments, etc. are lost when you close the software.) Please see: VirtualDJ Folder Permissions

Unnecessary software running in the background. Make sure that you do not have other unnecessary applications open at the same time as VirtualDJ that may be using excessive system resources.

Newer MacBook Pro models have two video cards - One basic card to extend battery life and a higher performance card for better graphics performance. Make sure that the higher performance card is enabled by going to System Preferences -> Energy Saver and choosing Graphics: -> Higher Performance